Stress Psychophysiology The Stress Response Stress Psychophysiology

The Brain Two major components Upper part: Cerebral cortex (thinking functions) Lower part: Subcortex (physiological processes)

Subcortex Includes the Limbic System (“seat of emotions”) Thalamus Hypothalamus See Figure 2.1 (p.24) Diencephalon

The Brain Hippocampus (sounds the stress alarm) Cerebellum (coordinates body movement) Pons (regulates sleep) Medulla oblongata (heart beat, respiration)

Stress and Its Pathways The hypothalamus activates the following under a stress response: Autonomic nervous system Immediate fight-or-flight response Hormone balance/body temperature/blood vessel width Endocrine system Short-term and long-term stress response Hormones that regulate physiological functions

Autonomic Nervous System Two systems working together during immediate stress: Sympathetic (responsible for expending energy) Parasympathetic (responsible for conserving energy) Figure 2.6 shows innervation of both divisions of the ANS (p.32)

Endocrine System Includes glands that secrete hormones Hormones travel through the blood stream These hormones change function of bodily tissues Specific hormones see figure 2.2 (p.26) Epinephrine, norepinephrine, Corticoids, Thyroxin, Vasopressin, Oxytocin See Figure 2.3 (p. 27)

The “Response” Flow Chart Life A Perceived threat Hippocampus (Alarm) Alarm, you will have an emotion Limbic System (Seat of Emotions) Emotional response will lead to a physical one Reticular Activating System Connection between mind/body Hypothalamus (Supervisor) Turns on Endocrine and Autonomic systems

The “Response” Flow Chart (cont.) Endocrine System (Hormones) Vasopressin-helps move blood through by increasing water in the blood Cortisol-increases blood glucose for battle. Also suppressed T-Cells, more likely to become ill. Autonomic Nervous System Sympathetic System- “ON” switch, increases energy level Parasympathetic System- “OFF” switch, decreases energy level

Endocrine System Vasopressin (pituitary gland) Increases blood permeability to water Increases blood volume Increases blood pressure Cortisol- primary glucocorticoid (adrenal gland) Increases blood sugar/ gluconeogenesis (mobilizes free fatty acids) Decreases T-lymphocyte production Thyroxin(hypothalamus) Accelerates heart rate Increases gastrointestinal motility Increases anxiety